'Good morning' 12 PM to 2 PM: Lunch break. 2 PM to 4 PM: Presentations. 'Good afternoon' 4 PM to 4:30 PM: Break. 4:30 PM to 12 PM: Presentations When greeting the audience: 'Good evening' even if it's 4:30 in the afternoon???? That is a bit unlikely, but for this session I would indeed begin with Good evening. / 'Good evening' even if it's 11PM??? More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.